Comorbid condition cause worse clinical outcome in PD The current study assessed the courses of Panic Disorder (PD) in consideration of the comorbid conditions. Patients with DSM-IV- diagnosed PD were assessed using the PD follow-up Questionnaire, Panic & Agoraphobia Scale, Hamilton Depression Rating Scale and State-Trait Anxiety Inventory. SCID (Structured Clinical Interview for DSM-IV) was used to determine comorbidity, and all participants were received to one year follow up. Comorbidity assessment showed that the threshold comorbidity decreased, although the sub threshold comorbidity increased at one year follow up. PD symptom severity was decreased but sub threshold panic symptoms continued to be present within the course of the illness. Presence of agoraphobia and duration of disease were significantly related with higher Panic & Agoraphobia Scale scores in the second assessment, and these relationships were independent from the treatment process. Even if the comorbidity and the severity of panic decrease with treatment, sub threshold panic and comorbid symptoms may still resist in panic disorder.